1. Field of the Invention
The present invention relates to a combination of a base and an axle tube for a motor. In particular, the present invention relates to a combination of a base and an axle tube for a motor, wherein the base and the axle tube are engaged with each other through a positioning groove and a positioning protrusion.
2. Description of Related Art
FIG. 1 of the drawings illustrates a conventional structure of a base and ax axle tube for a motor. Such a structure is disclosed in, e.g., Taiwan Utility Model Publication No. 343808 entitled xe2x80x9cPOSITIONING STRUCTURE FOR A STATOR AND SENSING ELEMENTS FOR A MINIATURE HEAT-DISSIPATING FANxe2x80x9d. As illustrated in FIG. 1, an axle tube 11 is integrally formed on a base (not shown) of a motor and made of plastics. Further, the axle tube 11 has an outer periphery for tightly engaging with a circuit board 12 and a stator 13. A bearing 14 is mounted in the axle tube 11.
FIG. 2 of the drawings illustrates another conventional structure of a base and an axle tube for a motor. Such a structure is disclosed in, e.g., Taiwan Utility Model Publication No. 236471 entitled xe2x80x9cSTATOR STRUCTURE FOR A MINIATURE HEAT-DISSIPATING FANxe2x80x9d. As illustrated in FIG. 2, the base 10 includes an axial hole 101 and a flange extending upward from a peripheral edge delimiting the axial hole 101. The axle tube 11 is preferably made of metal and includes a lip 11a on an upper end thereof. A lower portion of the axle tube 11 is tightly engaged with the flange 102 of the base 10, and an outer periphery of the axle tube 11 is tightly engaged in a central hole 130 of a stator 13. And the stator 13 is retained on the base 10 by the lip 11a of the axle tube 11.
FIG. 3 of the drawings illustrates a miniature D.C. fan having a further conventional structure of a base and ax axle tube for a motor. Such a structure is disclosed in, e.g., U.S. Pat. No. 5,267,842. As illustrated in FIG. 3, the miniature D.C. fan includes a casing 1, a base 10, and an axle tube 11. The base 10 is made of plastics and supported by a plurality of ribs of the casing 1, and the axle tube 11 is integrally formed with the base 10. The axle tube 11 includes a plurality of shoulders 11b, 11c, and 11d for tightly engaging with a stator 13, a circuit board 12, and at least one bearing 14 (preferably ball bearing), respectively.
Although the structures shown in FIGS. 1 through 3 are simple and easy to assemble at a low cost, time-consuming lathing or drilling is, however, required for forming the inner periphery and the outer periphery of the axle tube 11 for accurately positioning and assembling with the circuit board 12, the stator 13, and the bearing 14. Further, the bearing 14 and/or the axle tube 11 are apt to deform when proceeding with the procedure for tightly engaging the bearing 14 in the axle tube 11. Further, the axle tube 11 may turn or move upward relative to the base 10, as the axle tube 11 is merely engaged with the base of the motor by means of tight fitting. Further, the base 10 and the axle tube 11 can only be used with the stator 13 of a single specification; namely, the base 10, the axle tube 11, and the housing 1 must be redesigned if the stator 13 is of another specification. As a result, when the motor using any one of the axle tubes 11 shown in FIGS. 1 through 3 turns, the rotational movement is not balanced and noise is generated. Further, the assembly and design for motors are less flexible. Further, the stator might be loosened, which leads to shortening of the life of the motor.
An object of the present invention is to provide a combination of a base and an axle tube for a motor, wherein the base and the axle tube are engaged with each other through a positioning groove and a positioning protrusion. The axle tube includes resilient hook rods for reliably assuring that a central axis of the stator is coaxial with a central axis of the bearing.
Another object of the present invention is to provide a combination of a base and an axle tube for a motor, wherein the axle tube can be quickly replaced for using with a bearing and a stator of different specifications.
To achieve the aforementioned objects, the present invention provides a combination of a base and an axle tube for a motor. The base includes a tubular body and an axial hole. A flange extends upward from a peripheral edge delimiting the axial hole and has an inner periphery. At least one positioning groove is defined in a lower portion of the inner periphery of the flange. The axle tube includes at least one protrusion on a lower portion of an outer periphery thereof. The axle tube is extended through the axial hole of the base, with the lower portion of the outer periphery of the axle tube being engaged with the lower portion of the inner periphery of the axial hole of the base and with the protrusion of the axle tube being engaged in the positioning groove of the base. At least one resilient hook rod is formed in the tubular body of the axle tube and has a hook for securely retaining a stator around the axle tube and for securely retaining at least one bearing in the axle tube.
Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.